I finished reading this a little ago and thought I would post about it. Unfortunately I haven't been really active in posting and it's partly because I now work from home, and I've become so sick of my desk space that I usually get up as soon as I'm done and go some place else. It is stunting some of my other activities too (paper journalling, art, linocut).
However! I honestly really enjoyed reading a lot of this. Note: I am not a biologist. I am just someone who likes science and really likes natural history and has been reading about it. And this was a book aimed at the non-scientist audience. It's very readable, has clear arguments and chapter summaries, and doesn't go into too much detail but instead summarizes the conclusions.
The chapter on natural selection - absolutely incredible. It was so satisfying to read. He got it right. He really, really did, and he wrote it in 1859, long before we knew how variation arose. He said that of the ways these mutations (I use this word, he doesn't) were created, "we are profoundly ignorant". And he still got it right. This is one of my favourite things about human beings - the ability to synthesize multiple, disparate, and small pieces of evidence into the right idea. I think it is so cool that we can look at what would be otherwise inconsequential detail, but using what we observe and thinking through the antecedents/results, can piece together truthful ideas.
Some of the chapters, like the ones on hybrids, I found hard to sort through or found not that interesting. One of the difficulties for me was just the gap in time and the different terms. Darwin talks about varieties versus species - species and subspecies? - and many other terms which have fallen out of favour. The general frustration over how difficult it is to classify species - the species problem - is one that I don't think we might ever solve. It's fundamentally the problem of where a species ends and one begins, and the fact that every individual in a population is ever so slightly different creates a giant headache. He struggles to explain the frequent sterility in crossing different species (eg often chromosomal anomalies - but of course, the recent news about the paddlefish x sturgeon cross means even us with all the intervening 150 years of knowledge are still sometimes surprised). There's also various Victorian concepts on primitive vs higher order animals are, and so on.
It interests me that Darwin opens not with natural selection, but artificial selection created by breeding. It makes sense - it is hard to deny the incredible changes that we have created even over our small lifespans for domesticated animals; doing so would pretty much invalidate whole hobbies and a great deal of agriculture. And also that pigeon-breeding has really gone out of fashion these days - while some activities like dog breeding apparently continues apace, we don't really seem to want pouter pigeons or whatever.
Also, I don't think I'll ever have the patience of many biologists in the painstaking, tedious process of crossing and recrossing various individuals to see how their offspring turn out. I have the highest respect but my god, that must take forever. And you have to hand-fertilize plants! Ahh!
In 1859 not only did we not know about DNA, or mutations arising from errors in copying the genome, gene flow & founders' effect, we also didn't know about tectonic plates and their movements, collisions, and the fact that the earth's continents have been reshaped many many times. Darwin talks about the distribution (biogeography) of species and how it seems that those isolated on islands are usually clearly seeded from the nearest land, and almost exclusively from animals and plants that can make the oceanic journeys - so birds and reptiles and many plants whose seeds can be dispersed by wind and water, but not large mammals, which would find it difficult to swim or raft so far, nor amphibians, who need fresh water. And he says quite pointedly that these patterns of living beings' habitats are cleanly explained by them having to disperse, but difficult to imagine why they would be individually created and put there in such odd patterns. But he struggles to explain the geological record and how fossils are preserved, or to explain why identical species are on different continents now. Because he doesn't know that one location might have been in a completely different location, he can only say that the fossil site might have been underwater at some point and therefore had sediment deposited over the animals, preserving them. And more than that, geology/geography is so imperfect here. This is before radiometric dating is possible - so none of them have any idea
how actually old anything is. They can infer that rock piled above is younger than the rock below, but how much further, no idea. Darwin mentions that they haven't found fossils before the Silurian, but it's hard for me to tell (as someone reading in 2020) if he means the Silurian as the GTS currently defines it (mid-Paleozoic, 443-419 mya), or a different definition, as the definitions have shifted over time. (Is this pre-split before they inserted the Devonian period? No idea. Will not muddle internal GTS memorization by trying to add the
history of the geologic time scale).
Reading about the imperfections of the fossil record is also interesting. I can't remember if he mentions how little of the earth's geology has been explored at that point, but it's pitifully small. With only Europe somewhat explored, and bits of Australia, America, and Canada, it's a pathetically small sample. Even the Burgess Shale, which is in (for an Englishman) accessible Canada, wasn't discovered until 1909 (and the full significance realized much later). So many incredible fossils still to be discovered and classified, which gives us such a better view of what ancient life was like - and with the advent much better stratigraphy using absolute dating, plus putting together dots so we can use eg molecular clock analysis to even estimate ages with DNA - it's such an incomplete picture of an (already) patchy record.
As someone who has spent significant time trying to wrap her head around how unbelievably long 4.5 billion years are, and has mostly managed to get an OK grasp on the GTS's periods and epochs, I enjoyed this passage:
He who can read Sir Charles Lyell's grand work on the Principles of Geology, which the future historian will recognise as having produced a revolution in natural science, yet does not admit how incomprehensively vast have been the past periods of time, may at once close this volume.
It's so hard! We are not equipped to think correctly about thousands of years, much less millions, tens of millions, hundreds of millions, thousands of millions.
In the last few chapters, he emphasizes that the system towards which naturalists trying to classify life are groping towards is one of genealogy, of descent. And he is right. I only wish I understood taxonomy better. I learned ecology and molecular biology well enough, but I never did taxonomy. I need a good book to help, but I miss having access to university libraries.
I also enjoyed that there is much namedropping of other scientists. He's clear in the text that various assertions are made by so-and-so, with whom he has a correspondence, and will namecheck this person or that on the subject of e.g. fossilized land-shells in Madeira.
However, it was really enjoyable to read in a lot of ways. I wish he could have seen the ensuing discoveries and all the evidence that has been collected. The last chapter, as he sums up all the chapters and puts forward his argument, is especially beautiful.
Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.
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